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ABSTRACT This paper considers the problem of predicting the rainfall over East Asia from multimode outputs. For this purpose, we propose a new multimode ensemble method based on regularized regression approach, which consists of two steps, the pre-processing step and the ensemble step. In the pre-processing step, we improve prediction from each model output using regularized regression, and in the ensemble step, we apply regularization-based regression method to combine the result from the pre-processing step. The main benefits of the proposed method are that it improves prediction accuracy, and it is capable of solving the singularity problem so that it can integrate many climate variables from multimode outputs for a better prediction. The proposed method is applied to monthly outputs from nine general circulation models ( GCMs) on boreal summer (June, July, and August) over 20 years (1983-2002). The prediction ability of the proposed ensemble forecast is compared with the observations and the outputs (prediction) from each GCM. The results show that the proposed method is capable of improving forecast accuracy by adjusting each model before combining. [ABSTRACT FROM AUTHOR]

In the context of climate change characterized by rising temperature and more extreme precipitation regimes, drought is one of the most relevant natural disasters. This paper presents maps of global drought frequency, duration, and severity for the periods 1951-1970, 1971-1990, and 1991-2010, to give an overview of the respective drought hot spots. Drought frequency is defined as the number of drought events occurred, drought duration as the number of months in drought conditions, and drought severity as the sum of the integral area below zero of each event. Because drought is mainly driven by rainfall deficits, we chose the Standardized Precipitation Index (SPI) as the base indicator to derive drought-related quantities. SPI-12 has been calculated on a monthly basis using a Gamma distribution fitted to a 60-year baseline period (1951-2010). Global grids (0.5° ×0.5°) of the Full Data Reanalysis Version 6.0 dataset provided by the Global Precipitation Climatology Centre (GPCC) have been used as precipitation data input. The regions most exposed to prolonged and severe droughts during 1951-1970 were the Central United States, the Argentinian Pampas, Russia, and Central Australia; during 1971-1990 they were Southern Chile, the Sahel, and Siberia; during 1991-2010 they were the Amazon Forest, the Congo River Basin, Mongolia, North Eastern China, and Borneo. A linear trend analysis between 1951 and 2010 shows a small global increase in each drought component, but drought frequency decreased in the Northern Hemisphere. The increase in drought frequency, duration, and severity is found to be significant in Africa, Eastern Asia, Mediterranean region, and Southern Australia, while the Americas and Russia show a decrease in each drought component. [ABSTRACT FROM AUTHOR]